The present invention relates to novel polymer compositions which contain amide, sulfonate and/or phosphonate groups and method of use, including, but not limited to, paper making methods, particularly as retention or strength aids.
Currently, filler levels in paper are limited, in part, by paper strength losses as filler levels increase. Minimum strength requirements prohibit the paper maker from adding more filler which is desirable because fillers are generally less expensive than the wood fiber that they replace. The ability to add more filler would allow the paper maker to reduce paper production costs by replacing the more expensive fiber. In order to achieve higher filler levels, the paper maker needs fillers, additives or processes which increase paper strength. Historically, the paper maker has used filler modification, wet end additives and fiber modifications to achieve higher strength levels in paper. Filler modifications have included changing filler type, changing filler particle size and surface treatments of fillers. Wet end additives have included synthetic and natural polymers such as polyacrylamides and starches. Fiber modifications have included changing fiber type and fiber processing.
In general, the paper industry is trending toward higher filler levels to reduce costs and as a result is continually looking for ways to improve paper strength. To achieve this, a new generation of strength aids is required for the paper industry.
In U.S. Pat. No. 3,709,780, there is disclosed paper products having improved strength properties by adding to the cellulose paper dispersion a chitin-based compound of a graft copolymer of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) onto a chitosan substrate.
In U.S. Pat. No. 3,692,673, there is disclosed polymers of acrylamido sulfonic acids, and their salts, which are useful as flocculants for aqueous systems.
In U.S. Pat. No. 4,555,558, there is disclosed water soluble terpolymers of AMPS; N,N-dimethylacrylamide; and acrylonitrile. These terpolymers are reported to provide high temperature fluid loss additives and rheology stabilizers for high calcium-containing brine clay drilling fluids.
In U.S. Pat. No. 3,926,718, there is disclosed the use of water-soluble block polymers having blocks derived from a water-soluble monomer and blocks derived from N-vinyl, pyrrolidone. These polymers are reported to perform as drainage and retention aids for paper webs where the polymer is added to a pulp slurry.
In U.S. Pat. No. 5,075,401, there is disclosed a graft copolymer made by a free radical reaction mechanism. The copolymer uses polymeric units of acrylamide, acrylic acid and/or AMPS.
An object of the present invention is to provide a polymer having varied substituent groups having varied functions or utilities. One specific objective is to provide a polymer useful for binding mineral fillers, particularly to polysaccharide materials, such as paper pulps and the like. Another object is to provide a polymer useful as a binder in non-paper applications, such as rubbers, sealants, plastics, modifiers, pharmaceuticals etc. Such and other objectives are achieved in that the present invention provides novel polymers having phosphonated and sulphonated substituent groups such that the polymer is multifunctional in its use. Optional amide substituents are used to reduce electrostatic charge density or for increasing hydrogen bonding. An advantage of the polymer is the flexibility of using it for multiple purposes. Other advantages will be discerned by those skilled in the art in familiarizing themselves with this specification.
One embodiment of the present invention is a polymer composition having a polymeric core, one or more phosphonated substituents effective for bonding with an inorganic material, and one or more sulphonated substituents effective for bonding with a polysaccharide material.
Preferably, the polymeric core comprises one or more polymer units selected from polymerizable monomeric units, such as by condensation or free radical methods, preferably from allylic units, epoxidic units, and vinylic units. The polymeric core can be composed of varying proportions or sequences of substituted or unsubstituted monomeric (or polyrperic) units of allylic units, epoxidic units and vinylic units. Not all allylic unit, epoxidic units, or vinylic units need be the same as the other respective allylic units, epoxidic units, or vinylic units, but they can be. Such difference can result from hydrolysis reactions, among others, and whether intended or not. Such allylic, epoxidic and vinylic units can have one or more of the phosphonated or sulphonated substituents attached before or after polymerization. Such units of the core can be repeating in a predictable sequence or repeat randomly.
An allylic unit can be one derived from a compound with the moiety of CH3CH2xe2x95x90CHxe2x80x94. A preferred allylic unit is a polyacrylamide unit. The epoxidic unit can be one derived from a compound with the moiety of 
The vinylic unit can be derived from a compound with the moiety of CH2xe2x95x90CHxe2x80x94. A preferred vinylic unit is vinylphosphonate. Any one or more of the hydrogen atoms may be substituted before, during or after polymerization. The proportions of allylic units, epoxidic units, and vinylic units can vary widely, or a polymer can be composed of only one type of unit alone or various combinations thereof. Whether a polymer is made of only allylic units, only epoxidic units, only vinylic units or a combination of these types of units, the units of each type may be the same or different because of substitution. In a more preferred embodiment, the amount or proportion of the polyacrylamide units or the epoxidic units to the balance of the polymer composition is effective for reducing the electrostatic charge density of the polymer composition or for increasing the hydrogen bonding to the polysaccharide material or, more preferably, both.
Polysaccharide materials include cellulose, starch and other similar natural and synthetic glycosidic-linked saccharides. Preferred polysaccharides are cellulose, more preferably wood fiber and bagasse; even more preferably, cellulosic fibers for paper production.
In one embodiment, the present invention is a polymer composition comprising a various mixture of linking monomeric units, amide or epoxide monomeric units, phosphonated monomeric units and sulphonated monomeric units.
The preferred linking monomeric unit can be represented by the formula xe2x80x94CHxe2x80x94CH(R1)xe2x80x94, wherein R1 is hydrogen, a halogen or a lower alkyl.
The cationic or neutrally charged amide monomeric unit can be represented by the formula: 
wherein xe2x80x9cCxe2x80x9d is carbon; xe2x80x9cOxe2x80x9d is oxygen; xe2x80x9cNxe2x80x9d is nitrogen; xe2x80x9cAxe2x80x9d is an unsubstituted or substituted (C1-C6) alkylene or a hydrogen, wherein the substituents are independently selected from (C1-C3) alkyls and halogens, xe2x80x9cBxe2x80x9d is hydrogen, hydroxyl, or ether; preferably hydrogen. The nitrogen, N, can also be a quaternary nitrogen, including, but not limited to, combinations of the groups above; and xe2x80x9cR1xe2x80x9d and xe2x80x9cR2xe2x80x9d are each independently hydrogen, halogen or a (C1-C3) alkyl. xe2x80x9cAxe2x80x9d, if not hydrogen, is an (C1-C6) alkylene, e.g., methylene, ethylene, propylene, butylene, pentylene or hexylene. Such alkylenes can have a (C1-C3) alkyl substituent, e.g., methyl, ethyl or propyl. The halogen which can be a substituent on an alkyl or alkylene chain herein is selected from bromine, chlorine and fluorine atoms. For R1 and R2, the (C1-C3) alkyls are methyl, ethyl and n-propyl.
The preferred epoxide monomeric unit can be represented by the formula xe2x80x94CHRxe2x80x94Oxe2x80x94CH2, wherein R is hydrogen or lower alkyl or alkylene, e.g. alkylene having one to six carbon atoms.
The preferred phosphonated monomeric unit can be represented by the formula 
wherein xe2x80x9cPxe2x80x9d is phosphorus; xe2x80x9cOxe2x80x9d is oxygen; and xe2x80x9cAxe2x80x9d is selected from an unsubstituted or substituted (C0-C6) alkylene, wherein the substituent is independently selected from (C1-C3) alkyls and halogens, or from carbonyl (xe2x80x94COxe2x80x94), carbonylaminos (xe2x80x94COxe2x80x94NExe2x80x94, where xe2x80x9cExe2x80x9d hydrogen, hydroxyl, or ether), alkylenecarbonylaminos (e.g. xe2x80x94(CH2)xxe2x80x94COxe2x80x94NExe2x80x94, where x is an integer), carbonylaminoalkylenes (e.g. xe2x80x94COxe2x80x94NExe2x80x94(CH2)xxe2x80x94), or alkylenecarbonylamino-alkylenes (e.g. xe2x80x94(CH2)xxe2x80x94COxe2x80x94NExe2x80x94(CH2)xxe2x80x94); and xe2x80x9cDxe2x80x9d is a hydrogen proton or a salt moiety selected from aluminum, calcium, iron, lithium, magnesium, potassium, sodium, titanium and zinc ions. When in a salt moiety, the substituents are such that results in an electronic balance for the substituent group. The xe2x80x9cAxe2x80x9d is an (C0-C6) alkylene, e.g., nothing, methylene, ethylene, propylene, butylene, pentylene or, hexylene. However, such preferred alkylenes can have one or more (C1-C3) alkyl substituent(s), e.g. methyl, ethyl, or propyl. The halogen which can be a substituent on an alkyl chain herein is selected from bromine, chlorine, and fluorine atoms. Such halogens can be substituents on the alkylene chain also. When xe2x80x9cAxe2x80x9d is represented as xe2x80x94C(xe2x95x90O)xe2x80x94N(xe2x80x94E)xe2x80x94 then E is hydrogen, hydroxyl, or ether; preferably hydrogen. The nitrogen, N, can also be a quaternary nitrogen, including, but not limited to, combinations of the groups above.
When xe2x80x9cDxe2x80x9d is a hydrogen proton, xe2x80x94PO3xe2x80x94D can be represented as xe2x80x94P(xe2x95x90O)(xe2x80x94OH)(xe2x80x94OH). When xe2x80x9cDxe2x80x9d is a salt moiety, then xe2x80x94PO3xe2x80x94D can be shown by examples as
xe2x80x94(PO3)xe2x88x922(Na+1)2 when sodium is the moiety; or
xe2x80x94(PO3)xe2x88x922(Ca+2)1 when calcium is the moiety.
xe2x80x9cDxe2x80x9d may also represent a pairing of hydrogen and salt moiety. e.g. xe2x80x94(PO3)H+1Na+1.
The inorganic material is preferably a mineral containing material such as that which can be used for a filler in paper or non-paper products as hereinafter described. Although such is contemplated in the present invention, the invention is not necessarily limited to such inorganic materials. In some preferred embodiments, the inorganic material is a filler or other additive for paper compositions. In yet other embodiments, the inorganic material is a filler or other additive for non-paper compositions, such as plastics. A preferred inorganic material is one derived from or made with calcium containing matter, such as some clays or natural calcium carbonate. Another preferred inorganic material is precipitated calcium carbonate.
The preferred sulphonated monomeric unit can be represented by the formula 
wherein xe2x80x9cSxe2x80x9d is sulfur, xe2x80x9cOxe2x80x9d is oxygen; and xe2x80x9cAxe2x80x9d is selected from an unsubstituted or substituted (C0-C6) alkylene, wherein the substituent is independently selected from (C1-C3) alkyls and halogens, or from a carbonyl (xe2x80x94COxe2x80x94), carbonylaminos (xe2x80x94COxe2x80x94NExe2x80x94, where xe2x80x9cExe2x80x9d hydrogen, hydroxyl, or ether), alkylenecarbonylaminos (e.g. xe2x80x94(CH2)xxe2x80x94COxe2x80x94NExe2x80x94, where x is an integer), carbonylaminoalkylenes (e.g. xe2x80x94COxe2x80x94NExe2x80x94(CH2)xxe2x80x94), or alkylenecarbonylaminoalkylenes (e.g. xe2x80x94(CH2)xxe2x80x94COxe2x80x94NExe2x80x94(CH2)xxe2x80x94); and xe2x80x9cDxe2x80x9d is a hydrogen proton or a salt moiety selected from aluminum, calcium, iron, lithium, magnesium, potassium, sodium, titanium and zinc ions. When in a salt moiety, the substituents are such that results in an electronic balance for the substituent group. The xe2x80x9cAxe2x80x9d is an (C0-C6) alkylene, e.g., nothing, methylene, ethylene, propylene, butylene, pentylene or, hexylene. However, such alkylenes can have a (C1-C3) alkyl substituent, e.g., methyl, ethyl, or propyl. The halogen which can be a substituent on an alkyl chain herein is selected from bromine, chlorine, and fluorine atoms. Such halogens can be substituents on the alkylene chain also. When xe2x80x9cAxe2x80x9d is represented as xe2x80x94C(xe2x95x90O)xe2x80x94N(xe2x80x94E)xe2x80x94 then E is hydrogen, hydroxyl, or ether; preferably hydrogen. The nitrogen, N, can also be a quaternary nitrogen, including, but not limited to, combinations of the groups above. For example, when D is sodium, xe2x80x94SO3xe2x80x94D can be represented as xe2x80x94SO3xe2x88x92Na+. When D is an alkyl group, xe2x80x94SO3xe2x80x94D can be represented as xe2x80x94SO3CH3.
Non-limiting Examples of the Substituent Groups are:



Preferably, the molecular weight of the composition having the above core and substituents ranges from about 100,000 to about 20,000,000. When produced without the optional cationic or neutrally charged amide substituent, the more preferred molecular weight ranges from about 500,000 to about 5,000,000. When produced with the optional cationic or neutrally charged amide substituent, the more preferred molecular weight is about 500,000 to about 5,000,000.
The composition of the present invention can be produced with varying proportions or ratios of the molar units of the phosphonated substituents, the sulfonated substituents, and the optional cationic or neutrally charged amide substituents. The molar unit ratio of phosphonated substituents to sulfonated substituents can range from about 99/1 to about 1/99, but is preferably from about 45/55 to about 1/99, more preferably from about 10/90 to about 1/99. When the optional cationic or neutrally charged amide substituents are present in the produced polymer, such substituents are preferably predominate in proportion to the other substituents, preferably in a ratio of about 1/1, more preferable about 10/1 or higher relative to the phosphonated substituent. The ratio of the other two substituents to each other can remain as stated hereinabove. Accordingly, a preferred molar unit ratio of (cationic or neutrally charged amide substituents) to (sulphonated substituents) to (phosphonated units) is (from about 70 [preferably about 85] to about 90) molar units of cationic or neutrally charged amide substituents to (from about 0 [preferably about 10] to about 30) molar units of sulphonated substituents to (from about 0 [preferably about 5] to about 10) molar units phosphonated units. For examples, molar unit ratios of cationic or neutrally charged amide substituents/sulphonated units/phosphonated units of 85/10/5, 89/10/1 and 90/9/1. Other exact ratios are also preferred when in the stated ranges. While the sequencing of the units may vary according to the intended use, there is no general requirement or preference and the invention is not to be limited to any particular sequence illustrated herein. Additionally, the terminal units of the polymer , as well as other units and substituents, can be other than the units or substituents described as long as the presence of such does not interfere with the benefits of the present invention. Similarly, some degree of cross-linking may occur, but preferably is substantially absent.
In one preferred embodiment of the present invention the phosphonated substituent can be described as having the chemical structure of xe2x80x94PO3H; the sulphonated substituent as having the chemical structure of xe2x80x94C(O)NHC(CH3)2CH2SO3H; and the cationic or neutrally charged amide substituent as having the chemical structure of xe2x80x94C(O)NH2. Such polymer can be synthesized by the polymerization of varying proportions of vinylphosphonic acid monomers; 2-acrylamido-2-methylpropanesulfonic acid monomers; and acrylamide monomers. The following Table 1 is a non-limiting illustration of the polymers and molecular weights possible. (Molecular weights can be determined by an intrinsic viscosity method, such as one using Mark-Houwink-Sakurada constants.)
A non-limiting example of one of the polymers of the present invention can be exemplified by the following polymer segment structure: 
In a preferred embodiment, the phosphonated substituents are effective for bonding with a mineral filler. Such mineral fillers can be those typically used in paper making applications. Non-limiting examples of such fillers are clays, calcium carbonates (such as ground carbonates or precipitated calcium carbonates), and talcs. As will be understood, the phosphonated substituent(s) used and its(their) effectiveness will vary according to the type of paper making materials (e.g. pulps and/or fillers) and manufacturing conditions (e.g. temperatures, pressures, other chemicals) applied. xe2x80x9cBondingxe2x80x9d as used herein may include either or both of an acid-base interaction and ionic bonding to create a useful amount of affixation or affinity between the polymer and the mineral filler for the intended utility. Accordingly, bonding can be, but need not be, indicated by secondary measurements, such as retention or strength measurements in paper applications.
In a preferred embodiment, the sulphonated substituents are effective for bonding with a polysaccharide material. Such polysaccharide material can be those typically used in paper making applications, such as starches, fibers, thickening agents and the like. Non-limiting examples of such fiber materials are wood, bamboo, bagasse or other cellulosic biomass. Starch examples are cationic or neutral waxy maize, potato, tapioca, converted or chemically modified starch, synthetic starch, and the like. Thickening agents are the carboxymethyl family of thickeners and the like.
In another embodiment, the present invention is a polymer wherein the phosphonated substituents are effective for bonding with a mineral filler used for non-paper applications. In such application, the mineral filler is used in a composition which also contains material bonding with the sulphonated substituent of the polymer. Such non-paper applications can include, but are not necessarily limited to, applications involving natural and synthetic rubbers, sealants, plastics, paints (e.g. latex and emulsified), rheology modifiers, pharmaceutical tablets, etc. Such materials can include casted or extruded non-paper materials containing cellular or polymeric or polysaccharide material suitable for effective bonding with the sulphonated substituent, such as fillers useful for bulk or strength purposes.
The selection and amount of the optional cationic or neutrally charged amide substituent for reducing the electrostatic charge density and for hydrogen bonding will vary according to the selection of the phosphonated and sulphonated substituents.
In another embodiment the present invention is a polymeric composition comprising the novel polymers described hereinabove, which polymeric composition can have wide and varying characteristics relating to average molecular weights, molecular weight distributions, charge density, and type of monomeric units. Depending on the application, these characteristics can be adjusted. For instance, in a desired application the average molecular weight might be 1,000,000 with 85% of the polymers having a molecular weight of 1,000,000xc2x115%. As a further example, in another application, 85% of the polymers might have a molecular weight of 1,000,000xc2x150%.
Polymers can be classified as straight polymers and cross-linking polymers. Using known methods of analysis, such as Nuclear Magnetic Resonance Spectrocopy (NMR), the degree of cross-linking polymers (as a weight percent of the total composition) can be ascertained. In a preferred embodiment, the polymer composition of the present invention has a low degree of cross-linking and contains less than about 15 weight percent; more preferably, less than about 5 weight percent; and even more preferably, less than about 1 weight percent of cross-linking polymers.
In another embodiment of the present invention, instead of the phosphonated substituted having the above-described structure, the composition of the present invention has in lieu thereof a substituent comprising a derivative of a condensed phosphate, such as of a polyphosphate, pyrophosphate, or polyphosphoric acid (e.g. such as pyrophosphoric acid, metaphosphoric acid, superphosphoric acid or orthophosphoric acid).
In another aspect, an embodiment of the present invention is a method for improving the strength in paper comprising the addition of certain polymers compositions of the above polymer to a paper furnish optionally containing fillers. The preferred polymers are copolymers comprising acrylamide monomers and phosphonated monomers or sulphonated monomers or are terpolymers comprising acrylamide monomers, phosphonated monomers and sulphonated monomers. The addition of the polymer composition can be prior to the headbox of a paper machine in either the thick or thin stock. Split or multiple addition points and other strategies can be used. The amount added will vary according to the nature of the papermaking furnish and the intended use of the paper produced, but should be typically in the range of from about one pound to about five pounds of polymer composition per ton of furnish.
Unexpectedly, the polymer of the present invention in admixture with starch provides a synergistic increase in the strength of the paper produced. In one aspect, the synergistic effect is signified by the fact that no amount of either additional polymer or starch, when used alone, can provide an equivalent result to the combination of polymer and starch. The starch useable are those typically useable for papermaking. Such starch can be synthetic, such as ethylated or oxidized forms; or organic, such as potato based, preferably cationic potato starch, or corn based, such as cationic waxy maize. When both polymer composition and starch are added to paper furnish, the points of addition for each can be at various points upstream of the headbox. The polymer is preferably added to the thick stock and preferably before the addition of the starch. Split addition of each can be performed. Use of such polymers alone and in combination with starch improves the strength of paper formed with the polymers. Such strength improvement can conveniently be measured using known methods, such as breaking length, mullen burst and Scott bond methods.
Accordingly, one embodiment of the present invention is a process for the production of paper comprising the admixing of starch and a polymer composition comprising one or more polymers of the group consisting of acrylamide polymers, acrylamide polymers co-polymerized with a monomer containing a pendent sulfonic acid group or a phosphonic acid a group, and terpolymers of acrylamide co-polymerized with both a monomer containing a pendant sulfonic acid group and a monomer containing pendant phosphonic acid group. Such admixing occurs prior to or during the preparation of the furnish before providing the furnish to the paper machine. The sequence of the admixing can be before, during or after the addition of the starch and polymer compositions to the furnish, preferably before. When the starch and polymer composition is added to the furnish separately, the preferred order is to add the starch first. The polymer compositions are those described hereinabove.
The preferred process comprises effectively admixing the starch and polymer compositions to produce a paper sheet having a strength unexpectedly significantly greater than when either the starch or polymer composition is used alone, preferably at least about 15% greater, more preferably at least about 50% greater. Even more preferably at least about 100% greater.
In another aspect, an embodiment of the present invention is a process comprising effectively admixing the starch and polymer composition to produce a paper sheet having an unexpected synergistic increase in strength over the strength when either starch or polymer composition is used alone. Such xe2x80x9cSynergistic Increasexe2x80x9d is measured by comparing the strength attained by the combination of starch and polymer composition over the absence of both starch and polymer composition in comparison to the additive sums of the separate increases in strength of each of the starch and polymer composition alone over the absence of both starch and polymer compositions in the formed paper. Stated in the form of an equation:
xe2x80x83SI=[(SCxe2x88x92SA)/(SA)]xe2x88x92[(SSxe2x88x92SA)/(SA)+(SPxe2x88x92SA)/(SA)],
wherein SI is the synergistic increase, SC is the strength of the paper with the combination of starch and polymer composition, SA is the strength of the paper in the absence of either starch or polymer composition, and SS and SP are the respective strengths of paper with starch and polymer composition alone. The presence of a meaningful value of SI (e.g. that over experimental artifacts) is considered significant and unexpected as indicative of a result better than additive effects. In a preferred embodiment, the synergistic increase is one such that no amount of additional polymer or starch alone when singularly present will provide the equivalent strength provided by the inventive combination of polymer and starch for a given weight percent of inorganic (e.g., filler) material.
The amount of starch useable will vary in accordance with the particular furnish and paper being produced. Such amounts can typically range from about five to about fifty pounds per ton of paper. Similarly, the amount of the polymer composition can typically range from about one to about ten pounds per ton of paper.